Especially in larger brake installations, such as for trucks, overtravel of a brake rod is indicative of a number of potential problems. Although the actual amount of allowable brake rod travel varies from model to model, generally no more than about 2 inches of travel will be tolerated anywhere, because then there is trouble in the brake system. Overtravel most frequently reflects a need for adjustment of the brakes, and detection of the need for such an adjustment is a principal objective of this invention.
Monitoring the brake rod travel also monitors the operation of important brake components while the vehicle is in motion. For example, slack adjusters, both manual and automatic, can lose teeth and permit overtravel of the rod. Clevis pins can be lost, cams can be broken, drums can become cracked or bell-shaped, brake linings can become detached, and brake shoe rollers and pins can be lost. All of these can result in overtravel of the brake rod. With the use of this invention, such overtravel is detected and reported even while traveling, and the vehicle can be stopped before an accident occurs.
Thus it is an object of this invention to provide a monitor which is responsive to brake problems, and which gives warning whenever brake rod overtravel occurs.